Double barrel master cylinder brake system



Nov. 9, 1954 J. FALANGA ETAL DOUBLE BARREL MASTER CYLINDER BRAKE SYSTEM Filed Feb. 27, 1952 3A0. .mmfi E ZmMD a VF v m N. N W3 0 4 M ted SW3 poses new and useful improvements in anoperating assembly for thewheel brakes of a motor;vehic1e.--

Iii conventional :hydraiilic brakes'j ised on present day motor vehicles and employing a non-compressible liquid or brake flu d forscausing thewheel brakes to lie-applied in response to foot pressure on a pedal within convenient reach of the operator of the vehicle,-it is common practice topmploy only a singlemastercylinder as the source of fluid under pressure for ails-of, the brakes. Such arrangement has proven objectionable because aleak-at any single pnintin the system results in a loss'of pressure inseachof the wheel brakes. Therefore; a minor leak at any po nttin the system -will find the operator without brakes and at the complete mercy ofthe vehicl s inertia until. forward momentumihas expended-itself or the forward progress of the vehicle is stopped by hitting some solidobjectw l U I The present invention has as its primary ob ct the PI'OVISIOH' of a master cylinder unit -for the {hydraulic brake system of present day motor vehicles having s anof separate cylinders interconnected tofnnctioii in unison witheach. cylinder connected tothe brakes of two wheels of the vehicle in a manner to provide two separate braking systems forthevehicle so that leakage one system leaves theother system .free to .operate normally so that the VFhIClC Wlli have at least partial braking at all times.

Still further, the present invention proposes separate hose connections from each of. the cylinders of the master cylinder unit to, each .of two. different brakes of the vehicleone located at the fronton one side and the other located .at the, rear on: the other. s'ideso eachbrake system willbe .capableof applying an. equal braking force to.-.the two sides of thenvehicle when only one brake system is workingito retain the vehicle from side slipping or being. thrown into .auskid...

--As a furtherfobject the .present invention proposes a separate signal system operating in conjunction with each of the cyljindersof.thetmaster.cylindenunit fonoperatiiig signal lamps within convenientview of. the-operator of the vehicleforrindicating whenone of the. cylinders is not functioning for applying its respective brakes. i 1

It is a further object of the present invention topi'ovide animproved operatingiassernbly-for the wheel brakes of a motor vehicle which is simple and durable, which is effective for its intended purposes and which can be manufact-ui ed and sold at a reasonable cost. n v

For further comprehension of the invention, and (lithe objects and advantages thereof, reference will be "had to the following description and accompanying drawings, and to the appended claims in which the variousnovel features of the invention are more particularlyset forth. Y y

On the accompanying drawing forming a material part of the present disclosure:

Fig. 1 is a diagrammatic view illustrating the operating assembly for the wheelbrake's of a motor vehicle .ir'i jac cordancewith the present invention as it appears in plan when mountedonave'hicle'. I k 3 Fig. 2 is a'n enlarge'd s'ide elevational view 'of the master cylinder unit, per se.

Fig.3 is aplanvieW fFig with a, schematic wiring diagram of the signalmechanism applied. thereto..-

;;Fig. .4i is an enlarged :partial longitudinal sectional view taken on the l-inefi lfloffi-g. 2;. z

Fig. 5 is a view similar to Fig. 3., :but illustrating a cc 2,694,191 1,. Pitts-ed N Y: .i?5

modificatibnofthe-present invention and with portion thereof shown in section; 1 i t t v -F-i' 6 is an enlarged partial-transverse vertical sectional View taken on the line 66 of Fig. 5.

Fig. 7 an enlarged artial :transverse vertical sect tional view taken on the line 7 7 of Fig. 5. ,i

The brake system, according to the first form of the present invention illustrated inFigs. 1 to 4; ,is shown applied to a motor vehicle diagrammatically illustrated inp'lanin Fig.,1, having the usualf'ront wheels ltland rear wheels 11. The brake system is constructed to include a master -cyli nder unit. 15 having an-pair of adjacei t cylinders 16 andi17. =-Mounted over the cylinders 16 and 17 thereris a composite reservoir 18 having sep a v rate compartments foncontaining brakefiuid. in reserve for each of the cylinders; The separate compartments of the reservoir 18cai1 be best seen inFig. 3. The supply of; fluid within each of the compartments of the reservoir 18 can berenewed through separate fill openings in-the top thereof-closed by removable screw plugs 19, as gen- .erallyiknown in the art. i. I i.

Slidably mounted for axial movement within each of the-cylinders of the master brake unit 15,.there is a piston 20,- see Fig. 4

The pistons are urged rearward within the cylinders 16 and 17, to an inoperative posi tion; by theusual springs 21. t Pedal means is provided for moving thepistons 20 in unison against theaction .of thespr'in'gs 21 to force brake fiuidfrom/the .front-endsof the cylinders 16 and :17 to operate. the brakes of the-vehicle wheels lt) and 11 as will become clear as. this specification proceeds. The pedal means includes: a piston rod 22 extended coaxially from the rear-face of eachv ofathe pistons 20 with their rear ends slidablyextended from the rear ends of the cylinders: 16-a'ndW17. Theprojected rea'r ends of the piston rods 22 are joined by an integral crossbar 23 from .whicha'n extension 24 extends. The extension pro;- jects from the cross bar 23 intermediate of .its ends and parallel-to the length of the piston rods..22., The rear end of the extension 24 is pivotally joined to the usual pedal lever 25 by a pivots'pins26. The bottom end of the. pedal lever, 25, .as is gei ierally k nown in the art, is pivotedto a fixed. partof. the :veh-icles chassis and has its vtopsextendedprojected upwarld through a slot the floor boards of. the vehicleandtprovided .withthe usual pedal .21 to, :be engaged by the pperat0r.snri ht foot. When the pedal .27. ismoved-the pistons 29 will be meved in. unison within the.;cylinders 16. and 1'7 l iagainst thevaction of. the springs. .21 to force the brake fluid Extfinding from t he h se connector 2810f the cylinder 17,

he e s a pair fhsseslu mi t Th has: is connected t h 0 rom w el .9 t th ame s t t theweh l as th -s Whee to h sh the h e .39- s ,=s nm =te 1 1 0 232 scontdt z e0 rea he is the o he ide s thevehicle fromthe front wheel 10 to which the hose 3 -1 i con c ed-a. Th z ra s mentcf the. h s s .29 and... 9 andel. anewanine. e ts en m Fi .lniwmwhieh it wil e m dtha leach cvlin e 1 o 1 n at ssh brake eta inonl ivhtifihat on side f t e. ehiclea d a rear wheel a tthecther sideotthe ye isle-i. vTint it isappamnt that,thepresentinvention provides two sel aratebrake systems eachoperating twQEwheel brake of thevehiole. -.Wheln any one of.the brake systems isnot functioning. the vehicle islf-tuwith partial braking permitting the vehicle to be safety stopped until emergency repairs can. be made to restore the four wheel brakes. By having. eachscylinder operate a front and rear wheel on oppositesides .of theNehicle, the braking action of each cylinder; whendoperatin'g independently, will be proved retaining the car from being thrown into a side slip .or skid... A signal 33 operative in response to fluid pressures, is

indicating when the respective cylinder is not efiective 1 for applying its respective wheel brakes. The constructional details of the signals 33 are most clearly illustrated in Fig. 4 from which it will be noted that each signal includes a switch means having a hollow. casing 34 of separate sections 34*- and 34 screw threaded together. Clamped between the adjacent edges of the casing sections 34 and 34 there is afiexible diaphragm 35 which divides the interior of the casing 24 into separate compartments 36 and 37.

The diaphragm is constructed of rubber or any other flexible dielectric material which is inert when contacted by the usual brake fluids used in brake systems of the type proposed by the present disclosure.

Mounted concentrically on the side of the diaphragm 35 facing into the compartment 37, there is a single contact plate 38 of a conductivemetal. The contact plate 38 is secured to the diaphragm 35 by vulcanization or in any other manner. The other wall of the casing section 34 is formed with a concentric hole 39 into which a plug 40 is screwed. The plug 40 is formed of adielectric material and has mounted on its inner face a pair of spaced contacts 41 arranged to be bridged by the contact plate 38 when the diaphragm is deformed toward the plug Pins 42 are extended from the contacts 41 completely through the plug 40. The outer ends of the pins 42 are to flex them against the action of the springs 44 to engage -thecontact plate 38 with the contacts 41. If a leak should develop in either of the brake systems so that insufficient back pressure develops within the cylinders 16 and 17 to flex the diaphragms, the. plates 38 will not be con tacted with the contacts 41.

Each of the signals 33 further includes a lamp 49 or 50 connected in series with the pins 42 of the contacts .41 so that the lamp 49 will be'operated by the switch means of the right cylinder 16 and the lamp 50 will be operated by the switch means of the left cylinder 17. The circuits for each of the. lamps 49 and 50 can be traced from the leads 51 and 52 extended from a source of current on the vehicle. The lead 51 has a branch lead 51*- connected to one of the pins 42 of the switch mounted on the cylinder 16 and a lead 51 connected to one of the pins 42 of the switch mounted on the cylinder 16. The lead 52 has one branch 52 connected to one side of the lamp 49 and a second branch 52 connected to one side of the. lamp 50. A lead 53 extends from the other pin 42 of the switch mounted on the cylinder 16 to the other side of the lamp 49. Likewise, a lead 54 extends from the other pin 42 of the switch mounted on the cylin- Y der 17 to the other side of the lamp 50.

threaded and have nuts 43 mounted thereon to have electric leads attached thereto, as will become clear as-this specification proceeds. Positioned within the compartment 27 there is an expansion coil spring 44. The spring iiespective cylinder 16 or 17 of the master cylinder unit The tubes 46 of the signals 33 are joined to the cylinders 16 and 17 at points reached by the pistons 20When the supply of brakefluid within the cylinders would be considered dangerously low for safe operation of the brakes-a point at which operation of the brakes requires too much pedal, as the condition is referred to by those skilled in the art. During normal operation of the brakes which causes aback pressure on the reserve fluid within the cylinders 16 and 17, some of that back pressure will expend itself through the tubes 46 into the compartments 36 of the signal casings 34. That pressure will flex the diaphragms 35 against the action of the springs 44 and engage the contact plates 38 with the contacts 41 and close the circuits to be here-in-after described. I v

Extended rearward from the side of each of the tubes 46, there is a by-pass tube 47 which is connected to the side of the respective cylinder 16 or 17 rearward of the point where the tube 46 is connected. Each by-pass tube 47 is constructed of two parts-one integral with the tube 46 and the other threaded into the respective cylinder 16 or 17with-the adjacent ends of the parts connected by a union 48. The spacing of the axial centers of the tubes 46 and 47 is equal to thethickness of the pistons 20, as best shown in Fig. 4. Thus, when the supply of brake fluid reaches the dangerously low point, continued forward movement of the pistons will close the entrance to the tubes 46 and expose the discharge ends of the by-pass tubes 47. When that position is reached fluid forced into the compartments 36 to flex the diaphragms 35 will be discharged by the action of the springs 44 on the diaphragms 35 to discharge back onto Referring to the scheamtic wiring diagram of Fig. 3, f

it will be noted that the circuits described provide a series for each of the lamps 49 and 50 causing them to be illuminated when the contact plate 38 of the respective cylinder switch is engaged with the respective contacts 41 closing the respective circuits. The lamps 49 and 50 are to be mounted within view of the operator of the vehicle on the dashboard so that illumination of the lamps can be plainly seen. When only one of the lamps 49 or 50 is illuminated,- the operator will be immediately warned that something is wrong in the brake system con-' trolled by the lamp which is not lit and that the vehicle is being operated with only partial braking. Accordingly; the vehicle should be operated more cautiously at reduced speeds until emergency repairs can be made restoring the four wheel brakes.

Referring to the modification of the invention shown in Figs. 5 to 7, the master brake unit 15 has separate brake cylinders 16 and 17 releasably joined together to be individually replaceable when required. Each of.

the cylinders 16 and 17 has its individual reservoir 18 with a separate fill hole closed by a separate removable screw plug 19 The inner side of the cylinder 17 is formed with a longitudinally extended rib 60, see particularly Fig. 6, formed with a longitudinally extended groove 61 of dove-tailed cross-section and which opens toward the cylinder 16*. The side of the cylinder 16 is formed :with a longitudinally extended dove-tailed extension 62 17%- against longitudinal movement relative to one anthe cylinders 16 and 17 through the by-pass tube 47 to the for operating its respective brakes. At this point, it should be explained that the springs44 are pre-set to require a given pressure of the brake fluid against the diaphragms 35 other.

The holdnig means comprises a strip of metal 63 extended between the front ends of'the cylinders 16 and 17 One'end of the. strip of metal is secured to the cylinder l6 by a bolt 64 and the other end is secured to the cylinder 17 by. a bolt 64.

The piston rods 22. which extend from the rear ends of the cylinders 16f and 17 are provided with right angularly'bent portions 66 arranged in end alignment with the ends of the cross bar 23 carried byjthe ex-.

tension 24. Axially slidable and turnably mounted on the ends of the cross bar 23 there are sleeves67, see. Figs. 5 and 7. The sleeves 67 are internally threaded at their ends facing the ends of the right angularly bent portions 66. The right angularly bent portions 66 of the 7 portions 66 to positions in which the lengths of the sleeves 67 are equally divided between the cross bar 23 and the end portions 66 to effect a rigid connection between those parts.

The constructions described in connectionwith Figs. 5 to 7 provlde a convenient means whereby either of the cylinders 16 or 17% can be separated from'the other to be replaced when necessary without having to replace the complete master cylinder unit 15.

In all other respects, the form of the invention described in cormection with Figs. 5 to 7 is similar to the first form and like reference numerals are used to identify like parts.

The features of the present invention have been described in connection with that type of brake system employing a liquid as its operating fluid. However, it is appreciated that those novel features of the present invention can also be incorporated in brake systems employing other types of operating fluid such as air or the like, Without departing from the scope and intent of the present disclosure.

While we have illustrated and described the preferred embodiments of our invention, it is to be understood that we do not limit ourselves to the precise constructions herein disclosed and the right is reserved to all changes and modifications coming within the scope of the invention as defined in the appended claims.

Having thus described our invention, what we claim as new and desire to secure by United States Letters Patent is:

An operating assembly for the wheel brakes of a motor vehicle, comprising a master cylinder unit having a pair of cylinders each having a piston, a separate brake fluid compartment communicating with each of said cylinders, pedal means for moving said pistons in unison, each cylinder having a hose connection to the brake of a front wheel on one side of the vehicle and to the brake of a rear wheel at the other side of the vehicle, and a signal for each of said cylinders indicating when the respective cylinder is not effective for applying its respective brakes, said signals comprising switch means responsive to brake fluids mounted on each of said cylinders, a lamp for each of said switch means, each switch means including spaced contacts arranged to be bridged by a contact plate movable by fluid pressure, and circuits connecting each of said lamps in series with the spaced contacts of one of said switch means and a source of current, each of said switch means being joined to its respective cylinder to receive fluid under pressure from said cylinders at a point reached by the respective piston when the supply of fluid is dangerously low in the respective cylinder, and a by-pass tube connecting each of said switch means to the respective cylinders at a point rearward of said first-mentioned point to relieve pressure to the switch means when the pistons move to the dangerously low position within said cylinders.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,107,111 Etchison Feb. 1, 1938 2,141,358 Meeks Dec. 27, 1933 2,332,301 Cox Oct. 19, 1943 

